        program demo_reverse
        use M_strings, only: reverse
        implicit none
        character(len=:),allocatable  :: s
           write(*,*)'REVERSE STRINGS:',reverse('Madam, I''m Adam')
           s='abcdefghijklmnopqrstuvwxyz'
           write(*,*) 'original input string is ....',s
           write(*,*) 'reversed output string is ...',reverse(s)
        end program demo_reverse
